Basal Cell Carcinoma




Introduction

Basal cell carcinoma is the most common form of skin cancer. It's also the most easily treated and the least likely to spread. But though basal cell carcinomas are rarely fatal, they can cause extensive damage to surrounding tissue and bone if they're not removed.

Because basal cell carcinomas often take decades to develop, they once occurred almost exclusively in older adults. In recent years, though, the tumors have become much more common in younger people and are increasing every year among adults of all ages.

Basal cell carcinomas also have a high recurrence rate; if you've had one basal cell carcinoma, you have a good chance of developing another within five years. The risk is even greater if you've been diagnosed with two or more basal cell carcinomas or the cancer occurred on the trunk of your body.

Most basal cell carcinomas are caused by long-term exposure to ultraviolet (UV) radiation from sunlight. Avoiding the sun as much as possible is the best protection. Sunscreen is an important part of a sun-safety program, but by itself can't prevent basal cell carcinoma or other forms of skin cancer.

Signs and Symptoms

Basal cell carcinomas usually develop on sun-exposed parts of your body, especially your head and neck. A much smaller number occur on the trunk and legs. Yet basal cell carcinomas can also occur on parts of your body that rarely see the light of day.

Although a general warning sign of skin cancer is a sore that won't heal or that repeatedly bleeds and scabs over, basal cell tumors are likely to take one of these forms:
  • A pearly white or waxy bump, often with visible blood vessels on your face, ears or neck. The bump may bleed, develop a crust or form a depression in the center. In darker skinned people, this type of tumor is usually brown or black.
  • A flat, scaly, brown or flesh-colored patch on your back or chest. Over time, these patches can grow quite large — up to 10 or 15 centimeters (about 4 to 6 inches).
  • More rarely, a white, waxy scar. This type of basal cell carcinoma is easy to overlook, but it may be a sign of a particularly invasive and disfiguring cancer called morpheaform basal cell carcinoma.


Causes

Your skin consists of three layers — the epidermis, which is closest to the surface, the dermis and the subcutis. Basal cells, which produce new skin cells, are at the bottom or basal layer of the epidermis. Normally, the new cells push older cells toward the skin's surface, where the old cells die and are sloughed off. This process is controlled by DNA, the body's genetic blueprint. But when DNA is damaged — by solar radiation, for example — the process of cell death and renewal no longer occurs as it should. Instead, cells may grow out of control and eventually form a cancerous tumor.

Environmental factors
As with many other diseases, basal cell carcinomas seem to result from a combination of genetic and environmental factors. Most of the environmental damage to skin cells comes from exposure to UV radiation from sunlight. Although some studies show that the greatest harm occurs during childhood and adolescence, UV damage also appears to be cumulative, so the more time you spend in the sun, the greater your chance of developing skin cancer. Your risk increases even more if most of your outdoor exposure takes place in locales or at times of day when the sun is strongest.



Other environmental factors that can lead to basal cell carcinoma include:
  • Therapeutic radiation. Psoralen UVA (PUVA) treatments for psoriasis and X-rays to the head or neck increase your risk of basal cell carcinoma as well as of other, more serious forms of skin cancer. It can take years for skin cancers to develop, and many radiation-induced carcinomas that occur later in life may have had their origins in radiation treatments for childhood acne or ringworm. The likelihood that therapeutic radiation will cause cancer depends on a number of factors, including the pigmentation in your skin, the total dose of radiation you receive, and your medical status.
  • Chemical toxins. Arsenic, a toxic metal that's found widely in the environment, is a well-known cause of basal cell carcinoma and other cancers. Though arsenic contaminates the soil, air and groundwater, most people get their greatest exposure in food, especially chicken, beef and fish, and in wine grapes sprayed with arsenic-containing toxins. The U.S. Department of Health and Human Services estimates that the average American ingests 11 to 14 milligrams of arsenic every day. Farmers, refinery workers, and people who drink contaminated well water or live near smelting plants are likely to ingest much higher levels.
  • Immunosupressant drugs. People who take medications to prevent organ rejection after transplant surgery have a greatly increased risk of basal cell carcinoma, though symptoms may not appear for years after the operation.


Genetic factors
Several inherited disorders cause basal cell carcinoma or greatly increase your risk, including:
  • Nevoid basal cell carcinoma syndrome (Gorlin's syndrome). People with this rare genetic disorder have numerous basal cell carcinomas as well as pitting on their hands and feet, spine abnormalities, and cataracts.
  • Bazex's syndrome. This disorder is marked by numerous basal cell tumors on the face and by a lack of sweating and body hair.
  • Xeroderma pigmentosum. People with xeroderma pigmentosum, which causes an extreme sensitivity to sunlight, are at high risk of skin cancer because they have little or no ability to repair damage to the skin from ultraviolet light.


Treatment

A number of therapies exist for treating basal cell carcinoma; the most appropriate one depends on the type, location and severity of the tumor. Some commonly used basal cell carcinoma treatments include:
  • Electrodesiccation and curettage (ED and C). This treatment can successfully remove new basal cell carcinomas, but is less effective for recurring tumors. It's often used for tumors located on your trunk, arms or legs. During the procedure, your dermatologist removes the surface of the skin cancer with a scraping instrument (curette) and then sears the base of the tumor with an electric needle.
  • Surgical excision. In this procedure, which is used for both new and recurring tumors, your doctor cuts out the cancerous tissue and a surrounding margin of healthy skin. In some cases, you may have a wide excision, which involves removing additional normal skin around the tumor. To minimize scarring, especially on your face, consult a doctor skilled in skinreconstruction.
  • Freezing. This involves removing cancerous cells by freezing them with liquid nitrogen (cryosurgery). It's useful for tumors on certain parts of your body and for people with more than one tumor, but it has definite drawbacks, including crusting, slow healing and scarring.
  • Mohs' surgery. This is an effective treatment for recurring basal cell carcinomas and those that are large, deep, fast-growing, morpheaform or on your face. During the procedure, your doctor removes the tumor layer by layer, examining each layer under the microscope until no abnormal cells remain. This allows the entire growth to be removed without taking an excessive amount of surrounding healthy tissue. Because it requires particular expertise, Mohs' surgery should only be performed by doctors specifically trained in the procedure.
  • Laser surgery. In this relatively new therapy, a laser is used to vaporize superficial basal cell carcinomas. To minimize bleeding, lasers are sometimes used instead of scalpels during surgical excisions.
  • Topical treatments. Some superficial basal cell carcinomas are treated with creams or ointments. Tazarotene (Tazorac), a prescription cream normally used for acne, appears to be effective in preventing basal cell tumors. It may have a role in treatment as well, but it hasn't yet been approved for this use, as tests are ongoing. Other, approved topical treatments include imiquimod (Aldara) and 5-fluorouracil. These prescription medications require careful supervision because both can cause severe skin irritation as well as systemic side effects.
Prevention

Most basal cell carcinomas can be prevented. To protect yourself:
  • Avoid the midday sun. Sunlight is strongest between 10 a.m. and 4 p.m., so try to schedule outdoor activities for other times of the day, even in winter or when it's cloudy. You absorb UV radiation year-round, and clouds offer little protection from damaging rays. Keep in mind that sunlight is more intense when it reflects off water, sand and snow.
  • Use sunscreen year-round. Sunscreens don't filter out all harmful UV radiation, but they play a major role in an overall sun protection program. Wear a broad-spectrum sunscreen with a sun protection factor (SPF) of at least 15 when you go outside, year-round. Use about 1 ounce — the amount that fits in your palm — to cover your entire body, including your lips, ears and the backs of your hands and neck. Apply sunscreen 20 to 30 minutes before sun exposure and reapply it every two hours throughout the day, as well as after swimming or exercising.
    A sunscreen called Anthelios SX, which has been widely used in Europe, is now available in the United States. It offers better protection from UVA rays than do traditional broad-spectrum sunscreens and may be more effective in preventing skin cancer. Still, don't rely on any sunscreen as your sole means of sun protection.
  • Wear protective clothing. Because no sunscreen provides complete protection, it's important to also wear tightly woven clothing that covers your arms and legs and a broad-brimmed hat rather than a baseball cap or visor. Some companies sell photoprotective clothing. Your dermatologist can recommend an appropriate brand, or you can research this clothing online. And don't forget sunglasses. Look for a pair that provides full protection from both UVA and UVB rays.
  • Be aware of sun-sensitizing medications. Some common prescription and over-the-counter drugs make your skin more sensitive to sunlight. These include antibiotics, certain cholesterol, high blood pressure and diabetes medications, ibuprofen (Advil, Motrin, others), and the acne medication isotretinoin (Accutane). Ask your druggist about the side effects of any medications you take. If they make you more sun sensitive, take extra precautions.
  • Perform regular skin checks. Examine your skin often for new growths or changes in existing moles, freckles, bumps and birthmarks. Don't forget to check your scalp, ears, and even your buttocks. If you have had one or more basal cell carcinomas in the past, you and your doctor should be especially vigilant about checking for recurring tumors.
  • Get enough vitamin D. This vitamin may help lower the risk of certain cancers. Although it's normally produced by sunlight on your skin, many experts recommend getting your daily requirement of vitamin D through food or supplements.


Informations obtained from National Institute of Health.
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